Method for conditioning metal slabs

ABSTRACT

A slab conditioning system including a pair of rotatable leaves for supporting metal slabs and a conditioning tool platform mounted above the leaves and adapted to traverse the slab during the conditioning process.

United States Patent Fieser et a1.

METHOD FOR CONDITIONING METAL SLABS Inventors: Arthur H. Fieser, P.O. Box A,

Allison Park, Pa. 15101; Loreley S. Mobley, 4420 Sebald Dr., Franklin, Ohio 45005 Filed: Oct. 3, 1973 Appl. No.: 403,116

Related U.S. Application Data Division of Ser. No. 305,794, Nov. 13, 1972, Pat. No. 3,829,072.

U.S. Cl. 148/95 Int. Cl B23k 7/02 Field of Search 148/95, 9.6

References Cited UNITED STATES PATENTS 1/1942 Weidner et a1. 214/1 GA 1 Mar. 11, 1975 2,915,199 5/1957 Evans .i 214/1 OA 3,176,971 4/l 65 Hulton et a1 266/23 H 3,629,015 12/1971 Yonezawa ct a1. 266/6 S X FOREIGN PATENTS OR APPLICATIONS 876,429 9/1961 Great Britain 2.14/1 CA Primary ExaminerW. Stallard Attorney, Agent, or FirmRobert D. Yeager [57] ABSTRACT A slab conditioning system including a pair of rotatable leaves for supporting metal slabs and a conditioning tool platform mounted above the leaves and adapted to traverse the slab during the conditioning process.

1 Claim, 11 Drawing Figures PATENTED 1 1 PATENTEWRI 1 I 3.870.570 sumau g Fig.3

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1 METHOD FOR CONDITIONING METAL SLABS CROSS REFERENCE TO RELATED APPLICATIONS This is a division of U.S. application Ser. No. 305,794, filed Nov. 13, 1972, now U.S. Pat. No. 3,829,072.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the conditioning of metal slabs; more particularly to a system for conditioning the surfaces of metal slabs and method of operation therefor.

2. Description of the Prior Art With the increased demand for metal products having close tolerances in both chemical and physical properties, manufacturers have found it necessary to condition metal in the semi-finished state in order to insure its suitability for further processing; otherwise, excessive amounts of in-plant scrap metal are generated. The conditioning process is directed largely to the removal of defects in the surface of metal slabs, billets and the like, which defects, if not corrected, can cause fouling of equipment in subsequent rolling operations. These defects can also produce more serious physical defects in the metal processed in such rolling operations, making it unacceptable for shipment.

Typical of the problems associated with surface conditioning of metals are those presented in the manufacture of steel. The primary technique for removing surface defects in semi-finished steel slabs, billets and blooms is by scarfing. Scarfing consists of the applica-' tion of oxygen and gas to the steel surface, usually by a torch, to oxidize the steel and thereby generate elevated temperatures that cause the oxidized product and adjacent steel to become liquid, which is then blown away. To a lesser extent, surface conditioning of steel is also carried out by grinding, particularly on stainless steel, and by hand chipping.

Traditionally, scarfing has been a manual operation performed in a mill yard by a workman standing on a steel slab and manipulating a scarfing torch. This means, of course, that the slab must be cooled sufficiently to permit the workman to walk upon it. When one surface is completed, the slab is lifted with a chain or magnet held by an overhead crane and by some means turned over and lowered on the scarfed side; the manual scarfing process is then repeated. Slab weights have recently reached up to 40 tons or more and have thus made this turnover operation dangerous to workmen nearby. Moreover, scarfing produces heat and noxious fumes, thereby presenting health hazards to the workmen involved in the scarfing operation. Also the arduous nature of the operation rapidly fatigues the worker and reduces his productivity.

More recently, automatic scarfing units have been installed in some plants in an in-line relationship with rolling mills. Automatic scarfing units consist of a number of scarfing torches so designed that they form a pass on the mill; accordingly, steel may be scarfed in the hot condition. However, scarfing is virtually indiscriminate with automatic scarfing machines and may result in reductions in metal yield up to 3-4 percent, depending on the size of slab or bloom and the depth of scarfing.

Other attempts have been made to mechanize discriminate scarfing operations; for example, a billet scarfing machine is shown in U.S. Pat. No. 3,176,971. That patent, however, contains no suggestion of a solution for the problems associated with scarfing heavy slabs and, in general, discloses a machine that lacks the versatility required for slab scarfing.

The present invention overcomes the disadvantages and objections associated with present metal surface conditioning equipment and methods. Not only are more efficient operating procedures afforded with the present invention, but also personnel safety hazards are markedly reduced.

SUMMARY OF THE INVENTION The present invention provides a slab conditioning system comprising: a base; a pair of independently rotatable leaves each adapted to support a slab, each of the leaves being pivotally mounted to the base to rotate in a direction toward the other for transferring the slab from one of the leaves to the other; means forindependently rotating the leaves; and-a slab conditioning tool platform rotatably mounted above the leaves and adapted for translatory motion with respect to the leaves. Preferably, the translatory motion of the tool platform includes longitudinal, lateral and vertical motion with respect to a line parallel with and central of the pivotal axes of the leaves.

Further, the present invention preferably provides that each of the leaves is rotatable from a horizontal position through more than in a direction toward the other leaf and that the leaves each include a frame and slab stop means extending perpendicularly from the portion of the frame adjacent to its pivotal mounting to the base. The slab stop means of each of the leaves are preferably positioned to cooperate with the other in the transfer of the slab. Also, the present invention preferably provides that the means for rotating the leaves comprises lift cylinders operably connected between the base and each of the leaves.

The slab conditioning tool platform of the present invention preferably depends from an overhead support means positioned in a vertical plane central of the pivotal axes of the leaves. Preferably, the platform is adapted for at least 270 of rotation.

The present invention further provides, in a slab conditioning system, the improvement comprising: a base; a pair of independently rotatable leaves each adapted to support a slab, each of the leaves being pivotally mounted to the base to rotate in a direction toward the other for transferring the slab from one of the leaves to the other; and means for independently rotating the leaves. Preferably, liquid spray means are mounted on the leaves and adapted to discharge the spray simultaneously against the top and bottom surfaces of the slab being supported in an upright position by the leaves.

The present invention further provides a method for conditioning metal slabs comprising: (A) delivering a slab to a first rotatable slab support means from a first direction; (B) rotating the first slab support means to incline the top surface of the slab; (C) longitudinally traversing the top surface with a conditioning tool to selectively condition the top surface; (D) transferring the slab fromthe first slab support means to a second rotatable slab means; (E) rotating the second slab support means to incline the bottom surface of the slab; (F) longitudinally traversing the bottom surface with BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view, partially in section, of the present invention;

FIG. 2 is a plan view of the present invention;

FIG. 3 is a partial elevational view showing a slab in a raised position and the slab conditioning tool platform in working locations;

FIGS. 4-6 are partial elevational views showing the sequence of movement to accomplish slab turnover;

FIG. 7 is a partial elevational view showing a slab in a raised position on the opposite leaf and the slab conditioning tool platform in working locations;

FIG. 8 is a partial elevational view showing a slab removal technique;

FIG. 9 is an enlarged sectional view taken along line IXIX of FIG. 2;

FIG. 10 is an enlarged sectional view taken along line X-X of FIG. 1; and

FIG. 11 is a partial elevational view showing a slab being supported in an upright position and quenched.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, there is shown an I shaped pit 10 formed in the floor 12 of a mill area. Pit 10 is encased in concrete and has a concrete floor 14. A rectangular concrete bridge 16 having a top surface level with mill floor 12 spans pit 10 across the midpoint of the neck of the I. An elongated rectangular base 18 is supported on bridge 16 and the portions of the mill floor 12 extending on either side of bridge 16. Base 18 is formed of heavy gauge stock and includes a pair of central H-beams 20 extending longitudinally of base 18. The side edges of base 18 overhang bridge 16. The open portions of pit 10 on each side of bridge 16 are enclosed by removable floor plates 22 extending from the mill floor 12 to the overhanging side edges of base 18.

A slab handling unit, generally designated by the reference number 23, is mounted on base 18. Slab handling unit 23 includes a pair of rotatable leaves. For

convenience herein, these leaves will be referred to as leaf 1" and leaf 2" and are so designated on the drawings. Since leaf 1 and leaf 2 are of identical construction (except for certain differences which will be noted), only leaf 1 will be described.

Leaf 1 includes a frame 24 having a pair of spaced longitudinal frame members 26 and 28 and formed from heavy gauge I-beams. Frame members 26 and 28 are connected by transverse frame separators 30, 32,

34 and 36, also of I-beam configuration. Frame 24 supports top plates 37. Mounted on top plates 37, longitudinally above frame separators 30, 32, 34 and 36, respectively, are wear plates 38, 40, 42 and 44. Wear plates 38, 40, 42 and 44 are designed to support a slab resting on leaf 1.

Offset from the centerline of each of frame separators 30, 32, 34 and 36 and mounted on frame member 26 (nearest the centerline of base 18) are aligned slab stops 46, 48, 50 and 52. Slab stops 46, 48, 50 and 52 are formed of heavy gauge stock having uneven sides; each stop has a pair of spaced, transverse stiffeners joining the sides of the stop, the long side of which forms the face 54 of each stop. It should be noted that the slab stops of leaf 2 are also mounted in offset fashion but on opposite sides of the centerline of their associated frame separators from the slab stops on leaf 1. This oppositely offset mounting of the slab stops permits them to cooperate when leaves 1 and 2 are brought into facing relationship.

Leaf l is pivotally mounted to base 18 at 'four points along the edge of leaf 1 nearest the centerline of base 18. These mounting points coincide with the respective junctures of frame separators 30, 32, 34 and 36 with frame member 26. Since the structure of the mounting points is identical, only the one associated with frame separator 30 will be described and that by reference to FIG. 10. Frame separator 30 comprises an I-beam with a portion of the lower flange and web cut away as shown in FIG. 1. A horizontal plate 56 is connected to the remaining vertical web of frame separator 30. Mounting plate 58 is connected to the underside of plate 56 by means of bolts 60. A pivot plate 62 having an opening (not shown) therethrough depends vertically from mounting plate 58. The opening in pivot plate 62 carries a bronze bushing (not shown). Mounted on base 18 is a pedestal-64 which includes an I-I-beam 66 and a mounting plate 68 secured thereto. A pair of upright, spaced, parallel plates 70 are connectedto mounting plate 68 and are arranged on either side of pivot plate 62. Plates 70 each have an opening (not shown) aligned with the opening in pivot plate 62. A shaft assembly 69 is inserted into the aligned openings in plates 70, pivot plate 62 and/or the bushing carried by pivot plate 62. Shaft assembly 69 is fixed in place by keeper pin 72. Thus, pivot plate 62 (and' thus leaf 1) is rotatable about shaft assembly 69.

Rotation of leaf 1 is accomplished by means of a pair of upright hydraulic lift cylinders 74 positioned beneath the two central frame separators 32 and 34. Each cylinder 74 is pivotally mounted to the overhanging portion of base 18 at the upper portion of the cylinder barrel; the cylinder barrel extends through an opening in base 18 and into pit 10. The pivotal mounting of each cylinder 74 includes lugs 76 extending from opposite sides of the cylinder barrel and mounted in trunnions (not shown) carried by a pair of upright brackets 78 mounted to base 18. The ends of piston rods 80 associated with cylinders 74 are clevis mounted to the underside of their corresponding frame separators 32 and 34 as shown diagrammatically at 82. When cylinders 74 are actuated, the ends of piston rods 80 pivot about their mounting points to leaf 1 as it moves from the normal horizontal position shown in FIG. 1 toward the vertical position. At the same time, cylinders 74 pivot in their mountings to base 18 so that the lower ends ofcylinders 74 move within pit 10 in an are away from bridge 16. The pivotal mounting of cylinders 74 permits them to move leaf 1 through the vertical to an angle in excess of degrees depending upon the length of the cylinders.

Located at the two outboard corners of leaf 1 and in longitudinal alignment with cylinders 74 are bumper assemblies 83. As shown in FIG. 9, each bumper assembly 83 includes an upright tube 84 mounted to base 18 by means of mounting plate 86 and supported by brackets 88. A coiled spring 90 is inserted into tube 84. Spring 90 is capped by tubular bumper 92 having a pad 94 closing the top thereof. Bumper 92 is dimensioned to slide within tube 84 and normally extends above the top of tube 84. The corner of leaf 1 is supported by pad 94. Bumper assemblies 83 act as shock absorbers when leaf 1, supporting a slab, is lowered to the horizontal position.

Depending upon local conditions, the slab handling unit 23 may be situated under a crane girder or on a centerline of two adjacent buildings in space usually considered dead because of the crane hook approach. In the latter situation, the slab handling unit 23 could be used as a means for transferring slabs from one building to another. In any event, a workpiece conditioning tool platform, generally designated by the reference numeral 95, is suspended above slab handling unit 23 and adapted to traverse the approximate longitudinal centerline of base 18.

As shown in FIG. 1, workpiece conditioning tool platforms 95 includes an enclosed, air-conditioned pulpit 96 suspended above slab handling unit 23. Pulpit 96 is intended to carry an operator and suitable controls to perform the functions described hereinafter. Pulpit 96 is movable vertically by means of a pair of hydraulic or electric cylinders 98 mounted between pulpit 96 and pulpit support member 100. Other suitable means may be employed to provide vertical motion to the pulpit. Pulpit support member 100 is rotatably mounted for at least l80, but preferably 270, of rotation by well known means to a carriage member 102. Carriage member 102, in turn, is suspended from transverse rails 104 and able to move laterally therealong by means of suitable rollers (not shown). Rails 104 are suspended from longitudinal girders 106 and adapted for longitudinal movement thereon by means of rollers 108. Electric power, oxygen and fuel: are supplied to pulpit 96 through flexible conduits 110, 112 and 114, respectively, each having swivel means 116 therein. Conduits 110, 112 and 114 may be fed from reels or festooned above girders 106. FIG. 1 also shows an overhead crane hook 118 suspending an electric magnet 120 at the closest possible relative point of approach to pulpit 96. Pivotally mounted at the lower portion of pulpit 96 is a workpiece conditioning tool 122, in this case depicted as a scarfing torch. Workpiece conditioning tool 122 is designed to be manipulated and controlled as desired by the operator in pulpit 96.

By reference to FIGS. 1 7, a typical operating sequence of the present invention will now be described. The operation begins with the pulpit in Position 1 (see FIG. 2), well clear of slab handling unit 23 and any length slab which might be supported thereon for conditioning. Pulpit Position 1 is adjacent control station 124 which has the controls necessary to actuate slab handling unit 23.. Control station 124 is designed to permit the operator to manipulate the controls without leaving his station in pulpit 96. An identical control station 126 is located at the opposite side of slab handling unit 23, adjacent Pulpit Position 2.

Metal slabs requiring conditioning are delivered to slab handling unit 23 on delivery table 128. Movement of slabs on delivery table 128 may be facilitated by rollers as shown or other suitable means. With leaves 1 and 2 in the horizontal positions shown in FIG. 1, magnet 120 lifts a first slab 130 from delivery table 128 and places it upon leaf 1 in a horizontal position with a longitudinal edge abutting faces 54 of slab stops 46, 48, 50 and 52. Instead of the crane and magnet shown, other suitable means may be employed to charge slabs to leaf 1 including platens having rollers or air bearings mounted thereon.

The operator next actuates lift cylinders 74 of leaf 1 to raise slab 130 to a position where it is inclined at about a 45 degree angle (see FIG. 3). The operator then rotates pulpit 96 to a position where conditioning tool 122 is substantially perpendicular to the inclined top surface of slab 130 (as shown in solid lines in FIG. 3). The operator will then control pulpit 96 to traverse the length of slab 130 approximately above the centerline of base 18. As pulpit 96 traverses, the operator is able to maintain the conditioning tool generally in the same relative position to the inclined surface of slab 130 by manipulating his controls of the position of (i) pulpit lift cylinders 98, for vertical movement and (ii).

carriage member 102, for lateral movement. The maintenance of this relative position is especially important in conditioning operations such as scarfing, grinding, inspection and chipping which require close visual observation of the slab surface by the operator. The operr ator is further aided by the pivotal mounting of conditioning tool 122 which enables him to move tool 122 in the range shown in broken lines in FIG. 3.

Another unique advantage gained by the present invention is attributable to performing the conditioning operation while the slab is inclined. With this arrangement, the residue of the conditioning operation (e.g. the slag formed during scarfing) runs down the surface of the slab and drops onto the floor below where it can be conveniently collected. Thus. a clean slab surface is always presented for the operators inspection.

When the conditioning of the top surface of slab 130 is completed by making one or a multiple number of passes across the face of the slab, the operator continues the traverse of pulpit 96 until it reaches either Pulpit Position 1 or Pulpit Position 2. These positions are well clear of slab handling unit 23 and any slab thereon. The operator actuates lift cylinders 74 of leaf 2 to rotate leaf 2 toward leaf 1 until leaf 2 passes through the vertical and reaches a position about from its original horizontal position (see FIG. 4). While leaf 2 is being rotated, the operator keeps leaf 1 in its inclined position. Next, the operator actuates lift cylinders 74 of leaf 1 to rotate it toward leaf 2. When leaves 1 and 2 are substantially parallel (see FIG. 5), the top surface of slab is very close to the wear plates 38, 40, 42 and 44 of leaf 2; and practically all of the weight of slab 130 is being borne by slab stops 46, 48, 50 and 52 of leaf 1. It should be noted that in this position, the slab stops of leaf] are elevated slightly above the slab stops of leaf 2. Also, the offset positions of the slab stops on the facing leaves permit them to overlap and thereby makes possible the close relationship of the top surface of slab 130 to the wear plates of leaf 2. This feature affords a relatively soft transfer of slab 130 to leaf 2 as next described.

The operator then actuates the lift cylinders of both leafl and 2 to cause them to move together toward leaf 2 while maintaining a substantially parallel relationship. When the leaves are about vertical, the front surfaces 54 of the slab stops of both leaves will be about horizontal, thereby permitting the slab stops of leaf 2 to share the support of slab 130. As simultaneous rotation of the leaves continues, the slab stops of leaf 2 raise above the slab stops of leaf 1 and assume the entire burden of supporting slab 130. ln this condition, leaf 1 is serving only to steady slab 130. When leaf 1 has rotated slightly more than 90 from its original horizontal position, the operator stops rotation of leaf 1 but continues the downward rotation of leaf2 until the bottom surface of slab 130 is inclined at an angle of about 45 degrees (see FIG. 6). At the same time, the operator returns leaf 1 to its original horizontal position for receiving a new slab.

The operator then rotates the pulpit 180 to place conditioning tool 122 into correct position as shown in FIG. 7 and traverses the length of slab 130, performing a conditioning operation on the bottom surface of slab 130 as described above. When that conditioning operation is complete, the operator continues the traverse of pulpit 96 until it reaches either Pulpit Position 1 or Pulpit Position 2. There, the operator actuates controls at control station 124 or 126 to continue the rotation of leaf 2 until it reaches the horizontal position (see FIG. 8). Magnet 120 lifts slab 130 from leaf 2 and places it on exit table 132 of similar construction to delivery table 128. Slab 130 is then moved away from slab handling unit 23 for further processing. The operator may then repeat the entire operation just described with respect to a second slab. It should be mentioned that one or more cranes may be used to carry magnet 120 and these may be (and most likely are) operated independently of pulpit 96. Thus, when the operator of slab handling unit 23 has completed the conditioning of a first slab, a second slab already will have been placed into position on leaf 1. Thus, the time required to load and unload slabs from slab handling unit 23 is essentially integral with operating time.

it may be seen from the foregoing that the operator in pulpit 96 is able to perform a discriminate scarfmg operation, for example, on a hot slab. Further, he can carry out the operation without being subject to heat and noxious fumes and can turn the slabs without a dangerouslifting operation as is now commonly practiced. Further, he is not subjected to fatigue of heavy manual work, thus increasing his personal productivity. Further, because the tool is mechanically mounted rather than manually held as in present practice, he can employ larger, heavier tools thus enhancing personal productivity.

A further advantage may be realized'with the slab handling unit of the present invention if, for example, it is located near the run-off table of a continuous slab caster. Ordinarily, after slabs emerging from a continuous caster are sheared, they are stacked horizontally on a rail car and moved to a yard for air cooling. This cooling operation may require several days and because of the different cooling rate experienced by a slab surface directly exposed to air compared with a surface abutting another hot slab, bowing" of the slabs often occurs. 'A bowed slab is difficult to process and sometimes requires further treatment to make it usable.

Accordingly, slab handling unit 23 may be employed as a quenching unit for hot slabs. As shown in FIGS. 2 and 11, both leaves of slab handling unit 23 may be fitted with a series of spaced water pipes 134 having jet devices 136 of any well known type mounted thereon at spaced intervals. In this case, top plates 37 and some of the underlying longitudinal and transverse supports would be omitted. As shown in FIG. 11, a slab 138 is raised to the vertical position by the cooperative rotation of leaves 1 and 2 in the manner described above. In this position, jet devices 136 point directly at the large flat surfaces of slab 138 and discharge water sprays uniformly over these surfaces. By subjecting both-large surfaces of slab 138 to quenching liquid delivered at equal rates and for-equal time periods, equal cooling is enjoyed and bowing of the slab is reduced or eliminated.

What is claimed is:

l. A method for scarfing metal slabs comprising:

A. delivering a slab to a first rotatable slab support means from a first direction;

B. inclining said slab upon said first support means to expose the top surface of said slab;

C. longitudinally traversing said top surface of said slab with a scarfing torch to selectively condition said top surface of said slab;

D. transferring said slab from said first slab support means to a second rotatable slab support means;

E. inclining said slab upon said second support means to expose the bottom surface of said slab;

F. longitudinally traversing said bottom surface of said slab with said scarfing torch to selectively condition said bottom surface of said slab; and

G. discharging said slab from said second slab support means in a direction opposite from said first direction. 

1. A METHOD FOR SCARFING METAL SLABS COMPRISING A. DELIVERING A SLAB TO A FIRST ROTATABLE SLAB SUPPORT MEANS FROM A FIRST DIRECTION, B. INCLINING SAID SLAB UPON SAID FIRST SUPPORT MEANS TO EXPOSE THE TOP SURFACE OF SAID SLAB, C. LONGITUDINALLY TRAVERSING SAID TOP SURFACE OF SAID SLAB WITH A SCARFING TORCH TO SELECTIVELY CONDITION SAID TOP SURFACE OF SAID SLAB, D. TRANSFERRING SAID SLAB FROM SAID FIRST SLAB SUPPORT MEANS TO A SECOND ROTATABLE SLAB SUPPORT MEANS, E. INCLINING SAID SLAB UPON SAID SECOND SUPPORT MEANS TO EXPOSE THE BOTTOM SURFACE OF SAID SLAB, F. LONGITUDINALLY TRAVERSING SAID BOTTOM SURFACE OF SAID SLAB WITH SAID SCARFING TORCH TO SELECTIVELY CONDITION SAID BOTTOM SURFACE OF SAID SLAB, AND G. DISCHARGING SAID SLAB FROM SAID SECOND SLAB SUPPORT MEANS IN A DIRECTION OPPOSITE FROM SAID FIRST DIRECTION. 